^Looking west from Exit 101 near Bristol, Indiana, October 2022.
Interstate 90 runs east-west as a tollway along Indiana's northern edge, whether that northern edge is the shore of Lake Michigan or the border with the state of Michigan. The tollway carrying Interstate 90 is called the Indiana Toll Road, and it carries Interstate 80 in addition to Interstate 90 through all of Indiana excepting the western 21 miles. Interstate 90 enters Indiana via the Chicago Skyway, another tolled highway, becoming the Indiana Toll Road as it crosses from Illinois eastward into Indiana. From this point in the very northwest corner of Indiana, Interstate 90 heads east through Gary, South Bend, and Elkhart, to meet the Ohio border in the very northwest corner of that state. Interstate 80 joins Interstate 90 near Portage, Indiana, and the two designations are concurrent for 136 of the 157 miles traversed by the Indiana Toll Road, continuing east together onto the tolled Ohio Turnpike.
Exits and mile markers are numbered in increasing order from west to east; this scheme is customary for all American east-west highways. Most exits along the Indiana Toll Road, the conduit for Interstate 90 in Indiana, are trumpet spurs with toll booths on them.
The first exit from Interstate 90 in Indiana is labeled "Exit 0", as it sits right on the Illinois-Indiana border. Eastbound travelers see "Exit 107", since the eastbound offramp is still in Illinois. Onramps and offramps are provided for both directions along Interstate 90, making it a complete interchange to US Routes 12, 20, and 41 along Indianapolis Boulevard...
Exit 3 only provides access to/from the west on Interstate 90, and it leads to the northwestern beginning of Indiana Route 912, also known as the Cline Avenue expressway...
Exit 5 leads to US Route 41, which now runs along Calumet Avenue...
Exit 10 is for a spur to Indiana Route 912, which now runs north-south in Gary along Cline Avenue:
Exit 14A is a trumpet spur to Buchanan Street, but its signed as the way to Grant Street, a more important thoroughfare in Gary:
Exit 14B is a diamond interchange to Broadway, a street in Gary that carries Indiana Route 53:
Exit 17 is a trumpet spur to the northern end of Interstate 65, and to the surface highway carrying US Routes 12 and 20:
Exit 21 is an interchange leading to Interstate 94, which crosses over as a freeway running northeast-southwest; a ramp splitting from this one leads to Indiana Route 51 and US Route 6, and Interstate 80 is dropped off by Interstate 94 onto Interstate 90. From here east into Ohio, Interstate 80 runs concurrently with Interstate 90 on the Toll Road:
Exit 23 is just signed as the way to Portage, but it's also the way to the southern extent of Indiana Route 249...
Exit 31 is for Indiana Route 49, providing access to Chesterton and Valparaiso:
Exit 39 is for US Route 421, which connects to Michigan City and Westville:
Exit 72 ends a 23-mile drought of exits, leading to US Route 31's freeway bypass around the west side of South Bend; this exit is signed as a way to South Bend, Plymouth, and Niles (in Michigan):
Exit 96 is the "Elkhart East exit", connecting to County Route 17, which used to be part of Indiana State Route 17. The county road becomes Michigan Route 217 at the state border just a mile to the north, and this is reflected on the exit signage:
Exit 101 is a trumpet spur, like most of the other exits along the Indiana Toll Road, linking to Indiana Route 15, Bristol, and Goshen:
Exit 107 is the interchange home to US Route 131's southern terminus and Indiana Route 13's northern terminus. US Route 131 continues north from here to Constantine, Michigan, and Indiana State Route 13 leads south from here toward Middlebury, Indiana:
Exit 121 is for Indiana Route 9, signed as the way to Howe and Lagrange in Indiana (though the sizeable town of Sturgis, Michigan, is only a couple of miles north of here)...
Exit 144 appears after another 23-mile drought, and it leads to Interstate 69, a freeway helping travelers to access Lansing, Michigan, and Fort Wayne. A side ramp splits from the offramp here, allowing access to Indiana Route 120, Indiana Route 127, Orland, and Fremont:
Interstate 90, with Interstate 80 along for the ride, continues east into the state of Ohio after 157 miles in Indiana. The eastern continuation in Ohio is also tolled, and it's known as the Ohio Turnpike...